Within the last several years much interest has been focused upon the ways in which vertebrate rods and the pigment epithelium (PE) interact, especially with regard to the assembly, shedding and digestion of outer segment discs. However, the anatomical relationship between mammalian cones and the PE, and their interactions remain poorly understood. In this research project our efforts are concentrated in two general areas: first, in establishing the normal ultrastructural relationship between mammalian cone outer segments (COS's) and the PE by electron microscopy; and second, in describing the recovery or regenerative process which occurs when that normal intercellular relationship is experimentally altered or disrupted. We have designed several specific projects which should contribute to our understanding of COS-PE interaction in the mammalian retina: (1) To determine the normal relationship of COS's and the PE in the rhesus monkey retina; (2) To determine whether disc shedding from mammalian COS's can be triggered by light; (3) To examine the recovery of COS's and the PE following light-induced damage; (4) To examine the ultrastructural changes which occur after experimental retinal detachment and following surgical reattachment. This project should provide useful information in defining the ultrastructural changes which accompany macular disease and retinal detachment in humans.